The long term objective of this subproject is to impact our understanding of the relationship between vestibular processing and an important aspect of cognitive processing, attention. These investigators propose that vestibulo-spinal and vestibulo-ocular systems are largely automatic, such that they are free of attentional demands when adequate sensory information is available to the intact system. However, they believe that when sensory information is reduced or degraded attentional demands increase for successful integration in processing of vestibular information. Three experimental protocols are suggested. In all experiments, patients with peripheral vestibular lesions will be studied along with age matched and gender matched controls. In experiments one and three the investigators will examine vestibulo-spinal responses under different conditions of varying postular challenge. In experiment two vestibulo-ocular responses are to be examined using rotational vestibular stimulation concurrent to the performance on an auditory reaction timed task. Data analyses are well described such that the specific hypotheses associated with each aim in this subproject are matched to dependent and independent variables of interest. The physical resources for the conduct for the experiments described in this subproject are largely in place already and have been successfully used by these investigators.